Apparatus for testing signal impulse generators



May 22, 1956 K. HAGENHAUS ErAL 2,747,033

APPARATUS FOR TESTING SIGNAL IMPULSE GENERATORS Filed July 30. 1952 2Sheets-Sheet l May 22, l956 K. HAGENHAUS ETAL 2,747,033

APPARATUS FR TESTING SIGNAL. IMPULSE GENERATORS Filed July 30, 1952 2Sheets-Sheet 2 To Flbl nited States APPARATUS FOR TESTEN@ SIGNAL IMPULSEGENERATRS Kurt Hagenhaus, Berlin-Siemensstadt, and Gerd lRiester,Berlin-Charlottenburg, Germany, assignors to Siemens & Halske,Aktiengesellschaft, Munich, Germany, a German corporation ApplicationJuly 30, 1952, Serial No. 301,646

Claims priority, application Germany August 18, 1951 16 Claims. (Cl.179-1752) contacts disposed in distinct lirst and second groups r whichare for coordinate operation interconnected by rassociated circuitmeans. The control contacts and circuit means and also additionalcontrol means coacting therewith must be tested and supervised in orderto as certain and to secure proper operation.

The object of the invention is to provide for such impulse generatorstesting and supervising apparatus comprising switching devices, e. g.,rotary switches, for connecting potentials required for the generationof the impulses from the respective groups of control contacts totesting means so as to ascertain coincidence or simultaneous occurrenceof the impulses. One of these switches is adapted to successivelyconnect with the testing means potentials of the Iirst group of controlcontacts and the other switch is adapted to successively connect withthe testing means the potentials of the second group of control contactswhich coact in a coordinate manner with the control contacts of theiirst group.

Details of the invention will be described with reference to theaccompanying drawings Figs. l and 2 showing an embodiment thereof. Thedrawings should be placed side by side, with Fig. 2 at the right of Fig.l and with the correspondingly referenced line in aiignment.

The impulse generator, the operation of which is to be supervised andtested, comprises rst switching means or control contacts Nii NP23 whichare in a certain time sequence repeatedly successively actuated bysuitable means, e. g. by rotary cam means (not shown) and secondswitching means or control contacts NPz Niz, which are by similar meanssuccessively actuated in a different time sequence. The operation issuch that the contacts NPI NP23 are successively actuated during thetime when one of the contacts NPzi NPziS is in operated position.Accordingly, contacts NPi NP23 will be successively actuated during thetime when the contact NPzl is in its actuated position. The contact Nlziis thereafter restored to normal position, in which it is shown, andcontact NPz2 is actuated to alternate operating position. The contactsNPi NP23 are, during the operating interval of contact NPzZ, againsuccessively actuated as before. The successive actuation of thecontacts NPI NPZS is repeated for the duration of operation of each ofthe successively actuated contacts NPz (only some of these contactsbeing shown in the drawing) until contact NPzlS is nally actuated, whenthe contacts NP NP23 are again The impulses produced by such a genare:

2,747,933 Patented May 22, 1956 2. successively actuated for theduration of the actuation of contact NPzlS. This completes the operatingcycle of the impulse generator.

G11` G1299 indicate; rectiers disposed in thecircuits extending betweenthel contacts NPi-Nlzs' and NPZLNPZIS. The designations P11 PXillZindicate terminals at which the impulses'- produced bythe generatorappear during the operation thereof'and may therefore be termed impulsereceiving terminals.

in addition to the two groups of control contacts NPI NPZB and NizlNPziS thererk are provided. contacts NPs (right hand upperV section ofthe drawing) which produce synchronizing impulses, and contacts NPf(lower right hand corner of the drawing) for` producing successiveswitching and steppingimpulses. These contacts are also operated bysuitable means, e; g. rotary cam means (not shown). The contacts NPs areactuated upon starting the. rotation of the cam means which operate thecontrol4 contacts Nll-NPZS, and the contacts NPf are similarly operatedincident to the actua,- tion of each of the control contracts NP'zNP'z13.

There are also provided among other means, the rectiiers such asindicated G11, GH, Gl23-Gi24, G125, G146-Gi277, G1278, G1299. Theremaining rectiiers, as Well as resistances included in the impulsegenerator circuits, have been omitted to avoid eucumberin'g the drawing.The manner of operation by which 'the impulses are produced at theterminals Pi'i PXIHzs is described in detail in the previously mentionedcopending application Ser. No. 301,647.

The supervising and testing of the operations of the control contactsNPll NP23 and NPzl NPZILS, in their resting as welll as in theiractuated positions, is in accordance with the invention accomplished bythe apparatus shown in the drawing which includes two rotary switchescomprising the stepping magnets DWI and DWZ. The stepping magnet DW1operates the wipers adwl, bdw and cdwi. These switchwipersI are advancedin step with the actuation of the impulse generator contacts NPI NFZSLThe stepping magnet DWZ` operates the wipers adwZ, bdwZ, cdu/2, andddwZ. These latter wipers are advanced in step with the actuation` ofthe contacts NPzll NPzlS. Lamps LPl LP23 and LP LPXIII are provided forsignalling specific circuitpoints where faults are discovered, e. g.,the absence of a marker. impulse on a certain impulse receivingterminal. Lamps Silly StlA are provided for coaction with the lamps LPiLPZS and LPI LPXIII, to signalY the specific nature of faults discoveredin the course of the testing. rlfhe lamps shown at the right hand lowercorner of the drawing, marked LRol, LROZ, LR03, are operated to indicatefailure of the corresponding discharge tubes R03, R01, R02.

The operation is as follows:

The supervising and testing apparatus is started by actuating the key Tl(upper rightV hand. section of the drawing). Ground is thereby connectedto the startconductor m1 for starting the drive of the previouslymentioned rotary cam means which operate the various contacts. Thecontact N-Ps is thereupon operated and relays B andv H1 (winding l) willbe energized from ground on NPs, contact 1e, rectifier, contacts of keyT1, windings of H11 and B to #60; Relay B operates its contact 2b toconnect itself in a holding circuit over 3111 toV ground `at 4Z. AtContact 49h relay B completes an alternate circuit for maintaining theoperation of the drive circuit over the conductor anl' independent ofthe key T1. Relay H1 closes its contacts 6h31 and 7h1 to connect to thegrids G of the tube R03 potential which causes the tube to becomeconductive. Relay P3 energizes now over its winding I which is disposedin the anode circuit of the tube, the energizing; circuit extending overcontacts 8p3, 9d2, 10d1, to ground at key T2. Relay P3 actuates itscontact 11p3, thereby disconnecting the circuit extending over itswinding I and completing a holding circuit over its winding PSII. Thetube R03 eX- tinguishes. A certain potential has meanwhile been placedon the grids G2 of the tubes R01 and R02 over a circuit including thewiper adwl which is in zero position. A corresponding potential has alsobeen placed on the grids G1 of the tubes R01 and R02, over the wipersbdw2 and adw2 respectively. These tubes, R01 and R02, now becomeconductive.

Relay P1 (Winding I) in the anode circuit of the tube R01 energizes overcontacts 12p1, 9d2, 10d1, to ground at key T2, and relay P2 (Winding I)in the anode circuit of tube R02, energized over contacts 13p2, 9d2,:11, to ground at key T2. The relays P1 and P2 operate their respectivecontacts Mp1 and 15,01 and thus complete holding circuits over theirwindings PIII and PZII. The cam controlled contact NPf (lower right handcorner of the drawing) is closed at the time of these operations andrelay E energizes from ground on NP, 2lb, 2001, 19173, 18p2, 17p1, 16e,winding of the relay E to 60. Relay E operates its contact 26e, therebyconnecting itself in a holding circuit to ground at closed contact 27b.

The above described switching operations take place if the supervisingand testing device is in proper operating condition for carrying out thetesting. If it is not in .proper operating condition, e. g. due tofailure of a tube to operate, thereby preventing actuation of one ormore of the relays P1 P3, relay A1 (lower right hand corner of drawing)will become energized over a circuit including a contact such as 24p3,23,02, and 22121, and the corresponding signal lamp LRol, LR02 or LR03,key T3, contact 50e, winding of A1 to 60. Signal lamp LPr is at the sametime operated in parallel with the relay A1. The latter relay operatesits contacts 5101 and 2501 to provide a holding circuit for its ownwinding and to maintain the signal lamp operated, which indicates thefailure of a tube. These circuits may subsequently be opened byactuating the key T3.

As already described, relay E is energized it the supervising andtesting apparatus is in operating condition. Upon closing its contact28e, relay E causes energization of relay W (right hand bottom sectionof drawing) from 60, winding of relay W, 28e, wiper cdwl, -in zeroposition, cont-act 27b to ground. Relay W closes its contact 29W toproduce a stepping impulse for the rotary stepping magnet DW1 (righthand upper section of drawing) from ground at cam operated contact NPs,31e, 29w, DW1, to 60, so as to cause .this magnet to advance its wipersadwl cdwl. The stepping magnet DWZ for the wipers adw2 ddw2 receives asimilar stepping impulse due to the operation of contact W of the relayW to step its wipers to position l Relay W deenergizes when the wipercdwl leaves its zero position and the relays P1 P3 are deenergized bythe opening of the contact 10d1 which is actuated by the stepping magnetDW1.

The impulse generator has been started over the start conductor ani, asalready described, and therefore is operating. The cam controlledContact NlPzl is accordingly placed in its alternate or working positionin which it is maintained for an interval during which the contacts NP1NP23 are for the iirst time successively actuated. Responsive to closureof NP1 an impulse is produced which becomes effective on the grids ofthe tube R03 and on the grids G2 of the tubes R01 and R02 over a circuitincluding wiper adn/1 in position l. The tube R03 is not affected bythis impulse. Provided that the cam controlled contact NPzl is in itsworking position properly operable, the grid G1 of tube R01 will receivea potential over the wiper bdwZ in position 1 to make this tubeconductive. The contact NPI also connects current from -50 to thecontact NPz13, over the rectifier G1277, causing an impulse at the gridG1 of tube R02 over wiper adi/v2 in position 1 to make this tubeconductive. Relays P1 and P2 in the anode circuits of the tubes R01 andR02 become energized and place their windings II in holding circuits asdescribed before. The tubes R01 and R02 are again extinguished by theopening of the contacts 12,01 and 13p2.

The apparatus thus ascertains in position l of the wipers adw cdwl andadwZ ddwZ, whether the cam controlled contacts NPI and NPzl are inproper working order and whether the cam controlled contact NPz13 is inproper normal position, thereby also testing the proper conductivity ofthe rectier G1277.

The rotary stepping magnet DW1, is energized upon next successiveactuation of the cam controlled contact NPs from ground on Nps, 31e,34p3, 33p2, 32p1, DW1 to 60 and wipers adwl cdwl are therefore advancedto position 2. Contact ltldl is opened upon energization of the rotarystepping magnet DW1, thus deenergizing the relays P1 and P2 by openingthe circuts of their holding windings.

The cam controlled Contact NP2 is thereafter closed and if its operationis proper a potential will be connected to the grids G2 ofthe tubes R01and R02, over wiper adwl in position 2, while corresponding potentialsare connected to the grids G1 of these tubes over the wipers bdw2 andadn/2, as before. These tubes become again conductive, causing actuationof the relays P1 and P2 which connect their windings II in `holdingcircuits, thereby disconnecting the tubes, as already described. A testpotential is also connected to the cam controlled contact NPzlS (inresting position) over the rectiiier G1278.

Accordingly, the apparatus tests in position 2 of the wipers whether thecam controlled contacts NP2 and NPZI are in proper working condition andwhether the contact NPz13 is in proper normal position, and further,whether the rectier G1278 is properly operative.

If all these elements are in proper working order, the wipers aa'wi cdw1will be advanced to the next position, so as to ascertain in a similarmanner the operating conditions of the contacts NPS, NPzl, NPz13 andcorresponding rectifier. These test operations are repeated fromposition to position of the wipers until the Wipers adw1 cdwl are inposition 23 to test the operating conditions of the associated camcontrolled contacts NP23, NPzl and the rectifier G1299. The wipers arethen stepped to position 24.

Relay R (bottom right hand section of drawing) is in position 24 of theWiper cdwl energized from -6i), winding of R, wiper cdw1 to ground atcontact 27b. Relay R closes a circuit for energizing relay H (upperright hand corner of drawing) by actuating its contact 38r, the circuitextending from ground at contact 3912, 331', winding of H to 60. Relay Hactuates its contact 40h, thereby connecting its own winding in aholding circuit independent of contact 381', Relay H1 is now energizedover its winding II in a circuit extending from 60, winding II of H1,35:11, 36112, 371- to ground. The rotary stepping magnet DW1 receives animpulse over a circuit from 60, DW1, 413, 42M, 43W, 44e, to ground andsteps its wipers adwl cdwl to position 25. Contact 35:11, operated bythe stepping magnet DW1, disconnects the winding II of the relay H1 andthis relay deenergizes (winding I of relay H1 has been disconnectedpreviously upon release of the key T1). Contact 42h is opened responsiveto deenergization of H1 and the stepping magnet DW1 accordinglydeenergizes. The interplay between the stepping magnet DW1 and the relayH1 is repeated until the wipers adwl cdwl are again in position zero.Relay R deenergizes when the wiper cdwl leaves position 25.

In the zero position of these wipers relay W is again operated in acircuit from 69, winding of W, contact ZSe, wiper cdwl to ground on 27b.The rotary magnet DWI receives another stepping impulse over a circuitfrom 60, DWI, 29W, 31e, NPs to ground and the wipers adwI edwI arestepped to position l. The rotary magnet DWZ is now also energized from60, DWZ, 3lw, 31e, NPs, to ground, advancing the wipers adn/2 daw2 toposition 2.

Over the wipers adw2 in position 2 will now be tested the cam controlledcontact NPzI in its normal position and over wiper bdw2 will be testedthe operating condition of the cam controlled contact NPz2 in itsactuated position, all during the successive actuation of the camcontrolled contacts NPI NPZS. The wipers adwl cdw are, during suchtesting, successively advanced in step with the successive actuation ofthe contacts NPI NP23, as already described. The various rectifiers,which are correspondingly switched-in, are also coincidently tested, asexplained before. The tubes Rol` and R02 operate during this test phaselikewise, as already described, receiving the potentials for their gridsGI over the wipers adwZ and bdwZ.

After completing this testing phase, the wipers arlwl cdwl are againadvanced from their positions 24 and to the zero position and the wipersadwZ ddwZ are thereafter advanced to position 3 to repeat the test forproper coordinate cooperation of the contacts NPI NP23, with the nextsuccessive contact, such as NPzZ, etc. etc. to NPZI3.

Upon completion of the testing of the cooperation of the contacts NPINP23 with the contact NPZI3, the wipers ndwZ ddwZ will be in position13. The wipers adn/I cdwI are again advanced from their positions 24-25to zero position, relay R being energized in positions 24-25 of wipercdwl. The relay W thereafter energizes again over wiper cdwl to groundon contact 271) causing operation of the rotary magnet DWI which stepsits wipers adwl cawI to position l.

The rotary magnet DWZ is also energized, responsive to operation ofrelay W and advance its wipers adn/2 ddwZ to position 14. Relay Y (righthand center section of drawing) is energized in position 14 of wiperddwZ and remains energized through to position 25 thereof in a circuitfrom 663, winding of Y, wiper ddwZ to ground on contact 27b.

The wipers ndwI cdwI are in step with the actuation of the camcontrolled contacts NPI NP23 advanced from position l to position 24, asalready explained. The potential required for the tiring of the tubesRol R02, which is conducted to the grids GI of these tubes, is obtainedover the wipers adwZ and bdwZ in positions 14 to 25 thereof. Relay Rwill again energize when the wiper ca'wl reaches position 24, therebyagain closing its Contact 37r to actuate relay H1 by energizing itswinding Il. Relay Y being operated and having closed its contact 45y inthe circuit of the rotary magnet DWZ, this magnet will receive astepping impulse after closure of contact 42M. and will advance itswipers adwZ ddii/2. Contact 36u72 is opened by the actuation of themagnet DWZ, thereby disconnecting the winding II of relay HI. Theinterplay between the rotary magnet DWZ and relay HI advances the Wipersndw2. ddwZ to zero position. The wiper ddwZ leaves position 25 andthereby causes deenergization of relay Y.

Relay Z (left of relay Y) now operates in a circuit from 69, winding Iof Z, wiper ddwZ to ground at 27b. At contact 4Z, relay Z disconnectsrelay B and the latter disconnects H by opening its contact 391;. RelayE continues to hold over its own contact 26e and closes contact fiez toground at 47W. The rotary magnet DWI is now in interplay with the relayH1 actuated until its Wipers adwI cclwl are advanced to zero position.Relay R becomes deenergized and since contact 48h is closed, the windingII of relay Z is energized in opposition to winding I, over wiper cdwlin zero position, and Z i 6 accordingly deenergizes. Other relays whichare at this instant operated, thereupon become deenergized.

The supervisory and testing apparatus has in this manner ascertained theproper working condition of the mpulse generator. The testing may berepeated as desired, in accordance with exchange regulations.

The potentials required for the testing as indicated in the drawing aretapped from the exchange battery.

The following faults may be discovered in the course of the testing:

l. Absence of the marker impulse on one of the terminals PIIPXIII23.-The reason for the failure of a marker impulse to appear at oneor the other of the terminals may be due to the failure of one of thecam controlled contacts NPI NP23. In such a case there will not occurthe impulse for the grids G2 of the tubes R01 and R02 which is in properoperation conducted thereto over the wiper adwl in the correspondingpositions 1 23 thereof. The relays PI and P2 therefore fail to operate.The relay L (top center of drawing) will now be energized in a circuitfrom 60, winding of L, rectifier, contacts 53122, 34p2, 31e, NPs toground. Relay L operates its contact 541 (shown at the left thereof) toconnect its winding in a holding circuit to ground at key T2. One of thesignal lamps LPI LP23, corresponding to the respective faulty contactNPI NP23, will now be operated over the corresponding position of thewiper bdwl, in a circuit extending from 60, affected signal lamp,contacts 67p2, 55p1 or 56112, 571 to ground at 27b. In addition,depending upon the particular position of the wiper cdwZ on one of itsbank contacts 1 13, one of the signal lamps LPI LPXIII will be operatedover contacts 58p1, 6Ip3, SSpI or 56p2, 571 to ground at 2711.

The operation of one of the signal lamps LPI LPZS in conjunction withone of the signal lamps LPI LPXIII, designates the affected signalreceiving terminal PII PXIII23, on which the marker impulse failed toappear.

The signal lamp StLI is at such same time operated over contacts 70121,571, to ground at 27b, as a general signal to indicate that a markerimpulse has failed to appear.

A substitute impulse generator may now be put in operation and thefaulty generator may be checked and put in order. The key T2 is operatedto deenergize the relay L, thereby causing disconnection of the operatedsignal lamps.

2. Imp/'oper marker impulse at one of the terminals PI] PX1II23.-Suchcondition may be caused by the failure of one of the cam operatedcontacts NPzI NPZI3 to reach its full working position. In such a casethere will not appear a corresponding impulse (over the Wiper bdwZ) onthe grid GI of the tube R01 and such tube will not fire and thus fail toenergize the relay P1. However, the required impulse for the grid G1. ofthetube lR02 will be present by way of the wiper adw2 (over which thenormal or resting position of the cam controlled contacts NPZI NPZIS istested), so that R02 becomes conductive causing energization of relayP2.

Relay L now energizes again in a circuit from 60, winding of L,rectifier, contacts 52ml, 33122, 34p3, 31e to ground at NPs. Relay Lcompletes a holding circuit for its own winding at contact 54d. Afterclosure of contact 57i, there will be operated one of the signal lampsLPI L XIII corresponding to the position of the wiper czwZ, i. e.corresponding to the cam controlled contact NPZI NPZIS which failed tooperate. Contact 67,122 is open and the signal lamps LPI LP23 thereforeremain at rest.

The resulting signal (one of the lamps LPI LPXIII operated) designatesthe group of marker signal receiving terminals affected by the failureof the corresponding cam controlled contact NPzI NPz13.

The signal lamp StLl is operated as described before under thesubheading 1.

3. Short circuit in one of the rectfers G11 G1299.-lf one of therectiers is short circuited, there will be, during the actuation of oneof the associated cam controlled contacts NPzl NPZIS, a steady potentialon the impulse receiving terminal associated with the faulty rectier. Inthe various operating positions of the wiper adwl a potential will beconnected to the grids G of the tube R03 causing this tube to becomeconductive to energize the relay P3. A potential is at such time alsoconducted to the grids G1 and G2 of the tubes R01 and R02, so that thesetubes also become conductive to energize relays P1 and P2. Relays P1,P2, P3 being energized, the relay L will be energized from 60, windingL, rectifier, contacts 69])3, 31e to ground at NPs'. One of the signallamps LPI LPXIII, which corresponds to the faulty circuit, will now beoperated over a circuit including the wiper cdu/2 and contacts 59p36,69111, 63172. In addition the corresponding one of the signal lamps LPlLP23 is operated in a circuit including the wiper bdwl and contacts68;;3, 64,03, 571, to ground at 27h. The operation of the two lampsindicates the particular circuit (impulse receiving terminal) containingthe faulty rectifier. Signal lamp StLZ is in this case also operatedover a circuit including contacts 7p3, 571, to ground at 27b, toindicate as a general signal that a rectifier is short circuited.

4. One of the rectifers G11 G1299 is' ntermpted.-The proper potentialswill in such a case be conducted to the grids G2 of the tubes R01 andR02 but only R01 will become conductive because the proper tiringpotential for the grid G1 will be conducted only to this tube by way ofwiper bdwZ. Accordingly only relay P1 will become energized. The relay Lwill energize as before. One of the signal lamps LPI LPXIII, whichcorresponds to the circuit containing the faulty rectifier, will beoperated over wiper ddw2 after closure of contact 65p1, and thecorresponding one of the signal lamps LPl LP23 will be operated overcontacts 67p2 and Wiper bdwl.

The particular lamps which are operated in this manner signal thecircuit in which there is an interrupted rectifier. Lamp StL3 is in thiscase operated over contact 73p1 to signal the corresponding rectifierinterrupted condition.

In case there are additional cam controlled contacts provided which aree. g. successively actuated prior to the operation of the contacts NPINp23, to produce impulses for desired switching purposes, suchadditional contacts may also be tested and supervised. For example, foursuch additional contacts that may be provided may be connected to thecontacts 14-17 of the bank controlled by wiper bdwZ, so as to causetiring of the tube R01, if these contacts are in proper worker order. Anauxiliary relay may in this case be connected with the bank contacts14-17 to take care of the switching operations which control thestepping of the wipers adw2 ddw2. Additional signal lamps may for suchcases be provided which may be connected for operation over the wipercdw2 to signal faults of the additional contacts.

Several contacts NPsr and NPsz are provided for load distributingreasons, serving switching control purposes for other exchange equipmentcooperating with the impulse generator and subdivided into groupsindicated at GI and GII (right hand upper section of drawing).

Between these contacts is disposed the relay U. This relay becomes, forthe purpose of signalling, energized over one of the contacts responsiveto failure of the other contacts to switch-in the signal lamp StL4 overthe contact 66u. The relay U also closes its contact 75u (upper righthand corner of drawing) to connect its winding II in a holding circuit.

It may be mentioned in conclusion that electronic stepping means may besubstituted for the stepping switches 8 shown. Electronic switchingmeans may also be substituted for the contact means NPI NP23, as isdescribed in the previously mentioned copending application, Serial No.301,647.

We claim:

l. Apparatus for testing the operation of signal impulse generatorshaving a plurality of a rst type switching means and an individualconductor extending .from each of said rst type switching means andhaving a plurality of groups of control conductors each group having aplurality of control conductors one for each of said individualconductors and connected with such irst conductor and having an impulsereceiving terminal connected with each control conductor and having aplurality of a second type switching means one for each group of saidcontrol condoctors and having means for successively actuating saidsecond type switching means to connect a potential to the associatedgroup of control conductors and means for successively actuating saidfirst type switching means to connect a potential successively to saidindividual conductors and therewith to said control conductors toproduce impulses at said impulse receiving terminals of the group ofcontrol conductors associated with an actuated second type switchingmeans, whereby impulses are successively produced at the impulsereceiving terminals of the successive groups of control conductors; saidapparatus cornprising testing means, a iirst device for successivelyconnecting to said testing means the potentials successively appearingon said individual conductors by the successive actuation of said irsttype switching means, and a second device for successively connecting tosaid testing means the potentials respectively connected by said secondtype switching means to the groups of: control conductors respectivelyassociated with said second type switching means, and means in saidtesting means for ascertaining the simultaneous occurrence of saidpotentials connected thereto.

2. Apparatus for testing the operation of an impulse generator having aplurality of groups of impulse receiving terminals each group comprisingseveral terminals and having a plurality of rst type switching means forsuccessively connecting potentials to said terminals in each group andhaving second type switching means for successively connecting apotential to all said terminals in each group, the coincidence of saidpotentials on any of said terminals producing a signal impulse thereon;said apparatus comprising testing means, a tirst device for successivelyconnecting to said testing means the potentials successively connectedto said terminals by said first type switching means, a second devicefor successively connecting to said testing means the potentialssuccessively connected to said groups of terminals by said second typeswitching means, supervising means in said testing means for testing forthe coincidence of said potentials, means governed by said supervisingmeans responsive to establishing coincidence of said potentialsconnected by said iirst and second type switching means for controllingthe continuous operation of said rst and second device, signalling meansrespectively individual to said first and said second type switchingmeans, and circuit means controlled by said supervising means responsiveto failure to establish coincidence due to failure of the respectiveswitching means for operating the signal means corresponding thereto.

3. The apparatus defined in claim 2, wherein said testing meanscomprises a plurality of electron tubes, signal means respectivelyindividual to said tubes, and circuit means responsive to failure ofeither of said tubes for operating the corresponding signal means.

4. The apparatus detined in claim 2, comprising a rectifier associatedwith each of said impulse receiving terminals, signal means common to aplurality of rectitiers, and circuit means controlled by saidsupervising means for actuating said last named signal means jointlywith the signal means corresponding to the switching means which causedthe failure to establish coincidence.

5. The apparatus defined in claim 2, comprising a pair of steppingswitches respectively constituting said first and said second device,and means controlled by said stepping switches for governing theoperation of said signal means.

6. The apparatus defined in claim 2, wherein said testing meanscomprises a plurality of electron tubes, circuit means controlled bysaid device for connecting said potentials to said tubes, relay meansrespectively coacting with each of said tubes, and circuit meanscontrolled by said relay means for governing the operation of said firstand said second device.

7. The apparatus defined in claim 6, comprising signal meansrespectively individual to said tubes, and circuit means controlled bysaid relay means responsive to failure of either of said tubes foroperating the corresponding signal means.

8. The apparatus defined in claim 5, comprising additional common signalmeans, and circuit means for operating said additional common signalmeans coincident with the operation of said individual signal means.

9. Apparatus as defined in claim l, wherein said first type switchingmeans are successively actuated during the time of operative actuationof each of said second type switching means.

10. Apparatus as dened in claim 1, wherein stepping switches constitutesaid first and second device, each of said switches having bankcontacts, said first type switching means being connected to bankcontacts of one of said switches, and said second type switching meansbeing connected to bank contacts of the other switch.

l1. Apparatus as defined in claim 1, wherein stepping switchesconstitute said first and said second device, each of said switcheshaving band contacts, said first type switching means being connected tobank contacts of one of said switches and said second type switchingmeans being connected to bank contacts of the other switch, and meansfor successively stepping said other switch for successively connectingsaid second type switching means' to said testing means to test theoperatively effective actuated position and also the normal position ofsaid second type switching means.

12. Apparatus as defined in claim 11, wherein said other switchcomprises two wipers and bank contacts associated therewith, theactuated position of said second type switching means being tested bysaid testing means over one of said wipers and the normal position ofsuch switching means being tested by said testing means over the otherwiper conjointly with the testing of the actuation of the nextsuccessive first type switching means.

13. The apparatus defined in claim 1, comprising stepping switchesconstituting said first and said second device.

14. The apparatus defined in claim 1, wherein a first stepping switchconstitutes said first device and a second stepping switch constitutessaid second device, and means for advancing said second stepping switchby one step after each operating cycle of said first stepping switchduring which such first switch is successively advanced a plurality ofsteps.

15. The apparatus defined in claim 1, wherein a first stepping switchconstitutes said first device and a second stepping switch constitutessaid second device, means for advancing said second stepping switch byone step after each operating cycle of said first stepping switch duringwhich such first switch is successively advanced a plurality of steps,and control contact means for aecting the advance of said steppingswitches.

16. The apparatus defined in claim 1, wherein a first stepping switchconstitutes said first device and a second stepping switch constitutessaid second device, means for advancing said second stepping switch byone step after each operating cycle of said first stepping switch duringwhich such first switch is successively advanced a plurality of steps, aplurality of utilizing circuits connected with said generator, aplurality of control contact means respectively associated with saidutilizing circuits, supervising switching means cooperating with saidlast named control contact means, and circuit means for said supervisingswitching means and said control contact means whereby said supervisingswitching means become operative over one of said control contact meansresponsive to failure of another such control contact means, and signalmeans actuated by said supervising switching means responsive tooperation thereof.

No references cited.

